1999 Ford Mustang - Low mpg

by Marissa


I have a 1999 Ford Mustang 3.8 V6, with dual exhausts, dual intake along with am cold air intake.

My question is , would these additions cause low gas mileage? Because I am only getting about 10 miles per gallon, when I should be getting about at least 20 mpg in the city.

I am a female and don't know much about cars. I hope my question makes sense.


It sounds like there may be other issues. The first thing I'd ask you, is whether this problem with your Mustang was happening prior to the addition of the new parts?

Also, is there a check engine light showing?

Many times, when parts are replaced, something gets removed that should not have been.

What I'm wondering, is whether the oxygen sensors were either removed, or damaged when the swap to dual exhaust was made?

If either has happened, the engine's computer will switch to "limp in mode", which will kill performance and gas mileage.

Have a reputable mechanic, check it out.

Good Luck!

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